The Democratic Party of Japan criticized former Prime Minister Yukio Hatoyama on Friday for apparently siding with China over the ownership of the Japanese-administered Senkaku Islands in the East China Sea.
"The comments were irresponsible and hurt national interests," the main opposition party said in a statement. Hatoyama was one of the founding members of the DPJ and was chief of the party when it took power in September 2009, assuming the role of prime minister until June 2010.
At issue was an interview with Hatoyama that aired Tuesday in which he said he understood why Beijing argues that the Senkaku Islands are part of China.
The Japanese government, now led by the Liberal Democratic Party, reacted immediately, criticizing Hatoyama and saying his remarks contradict the Japanese government's stance that there is no territorial dispute between Japan and China over the Senkakus.
In the statement, the DPJ, which said it will lodge a protest against Hatoyama, said it "cannot overlook" such comments which are "different from the position taken by the DPJ-led government."
Also Friday, DPJ President Banri Kaieda told reporters in Tokyo, "I want him to consider (his) position when making comments."
The DPJ's move to immediately distance itself from Hatoyama -- who did not run in last December's general election and has retired from politics -- is out of fear that his remarks could undermine the DPJ's standing in the forthcoming upper house election given that Hatoyama was once the party president, political watchers say.
The DPJ lost power in the December election and it suffered losses in Sunday's Tokyo metropolitan assembly election.
Tokyo and Beijing remain at odds over the ownership of the Senkakus, with Japan saying the islands, which are known as Diaoyu in China, are an inherent part of the country's territory in terms of history and international law.